1. Field of the Invention
The present invention relates to a dual-sided semiconductor chip and a method for forming the chip and, more particularly, to a dual-sided semiconductor chip and a method for forming the chip with a conductive path through the chip that connects elements on each side of the chip.
2. Description of the Related Art
A dual-sided semiconductor chip is a chip that has electrical circuits on both sides of a wafer. Thus, unlike more conventional semiconductor chips that utilize only one side of a wafer, a dual-sided chip utilizes both sides of the wafer. As a result, packaged dual-sided semiconductor chips consume significantly less circuit-board real estate than conventional single-sided chips.
FIG. 1 shows a cross-sectional drawing that illustrates a dual-sided semiconductor chip 100. As shown in FIG. 1, chip 100 includes a wafer 110 that has a top side 112 and a bottom side 114. As further shown in FIG. 1, chip 100 also includes an electrical circuit 120 which is formed on top side 112, and an electrical circuit 122 which is formed on bottom side 114. Electrical circuits 120 and 122 typically communicate with the outside world via wires that are connected to pads that form a part of circuits 120 and 122.
Circuits 120 and 122 can perform related or unrelated functions. When related functions are performed, circuits 120 and 122 can exchange signals via a wire that is connected to a pad that forms a part of circuit 120 and a pad that forms a part of circuit 122. Although this approach allows circuits 120 and 122 to exchange signals, there is a need for alternate techniques of exchanging signals.
The present invention provides a technique for exchanging signals on a dual-sided semiconductor chip by forming a low-resistance, conductive path through the wafer that allows elements on one side of the wafer to exchange signals (voltages and/or currents) with certain elements on the other side of the wafer.
The method of the present invention forms a dual-sided semiconductor chip from a wafer that has a top surface and a bottom surface. The method includes the step of forming a first opening in the wafer. The first opening extends through the wafer from the top surface to the bottom surface, and has side-wall surfaces.
The method also includes the step of forming a layer of insulation material on the side-wall surfaces. The method further includes the step of forming a layer of conductive material to contact the layer of insulation material and fillup the first opening.
The present invention also includes a dual-sided semiconductor device that is formed on a wafer that has a top surface and a bottom surface. The device includes an opening that is formed in the wafer. The opening extends through the wafer from the top surface to the bottom surface, and has side-wall surfaces. The device also includes a layer of insulation material that is formed on the side-wall surfaces. The device further includes a column of conductive material that is formed to contact the layer of insulation material and fill up the opening. The column has a top surface and a bottom surface.
A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description and accompanying drawings that set forth an illustrative embodiment in which the principles of the invention are utilized.